1 /*-
2 * Copyright (c) 2015 Gleb Smirnoff <[email protected]>
3 * Copyright (c) 2015 Adrian Chadd <[email protected]>
4 * Copyright (c) 1982, 1986, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94
32 */
33
34 #include <sys/cdefs.h>
35 #include "opt_rss.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/eventhandler.h>
40 #include <sys/kernel.h>
41 #include <sys/hash.h>
42 #include <sys/mbuf.h>
43 #include <sys/malloc.h>
44 #include <sys/limits.h>
45 #include <sys/lock.h>
46 #include <sys/mutex.h>
47 #include <sys/sysctl.h>
48 #include <sys/socket.h>
49
50 #include <net/if.h>
51 #include <net/if_var.h>
52 #include <net/if_private.h>
53 #include <net/rss_config.h>
54 #include <net/netisr.h>
55 #include <net/vnet.h>
56
57 #include <netinet/in.h>
58 #include <netinet/ip.h>
59 #include <netinet/ip_var.h>
60 #include <netinet/in_rss.h>
61 #ifdef MAC
62 #include <security/mac/mac_framework.h>
63 #endif
64
65 SYSCTL_DECL(_net_inet_ip);
66
67 /*
68 * Reassembly headers are stored in hash buckets.
69 */
70 #define IPREASS_NHASH_LOG2 10
71 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
72 #define IPREASS_HMASK (V_ipq_hashsize - 1)
73
74 struct ipqbucket {
75 TAILQ_HEAD(ipqhead, ipq) head;
76 struct mtx lock;
77 struct callout timer;
78 #ifdef VIMAGE
79 struct vnet *vnet;
80 #endif
81 int count;
82 };
83
84 VNET_DEFINE_STATIC(struct ipqbucket *, ipq);
85 #define V_ipq VNET(ipq)
86 VNET_DEFINE_STATIC(uint32_t, ipq_hashseed);
87 #define V_ipq_hashseed VNET(ipq_hashseed)
88 VNET_DEFINE_STATIC(uint32_t, ipq_hashsize);
89 #define V_ipq_hashsize VNET(ipq_hashsize)
90
91 #define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock)
92 #define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
93 #define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock)
94 #define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED)
95 #define IPQ_BUCKET_LOCK_ASSERT(b) mtx_assert(&(b)->lock, MA_OWNED)
96
97 VNET_DEFINE_STATIC(int, ipreass_maxbucketsize);
98 #define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize)
99
100 void ipreass_init(void);
101 void ipreass_vnet_init(void);
102 #ifdef VIMAGE
103 void ipreass_destroy(void);
104 #endif
105 static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS);
106 static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS);
107 static int sysctl_fragttl(SYSCTL_HANDLER_ARGS);
108 static void ipreass_zone_change(void *);
109 static void ipreass_drain_tomax(void);
110 static void ipq_free(struct ipqbucket *, struct ipq *);
111 static struct ipq * ipq_reuse(int);
112 static void ipreass_callout(void *);
113 static void ipreass_reschedule(struct ipqbucket *);
114
115 static inline void
ipq_timeout(struct ipqbucket * bucket,struct ipq * fp)116 ipq_timeout(struct ipqbucket *bucket, struct ipq *fp)
117 {
118
119 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
120 ipq_free(bucket, fp);
121 }
122
123 static inline void
ipq_drop(struct ipqbucket * bucket,struct ipq * fp)124 ipq_drop(struct ipqbucket *bucket, struct ipq *fp)
125 {
126
127 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
128 ipq_free(bucket, fp);
129 ipreass_reschedule(bucket);
130 }
131
132 /*
133 * By default, limit the number of IP fragments across all reassembly
134 * queues to 1/32 of the total number of mbuf clusters.
135 *
136 * Limit the total number of reassembly queues per VNET to the
137 * IP fragment limit, but ensure the limit will not allow any bucket
138 * to grow above 100 items. (The bucket limit is
139 * IP_MAXFRAGPACKETS / (V_ipq_hashsize / 2), so the 50 is the correct
140 * multiplier to reach a 100-item limit.)
141 * The 100-item limit was chosen as brief testing seems to show that
142 * this produces "reasonable" performance on some subset of systems
143 * under DoS attack.
144 */
145 #define IP_MAXFRAGS (nmbclusters / 32)
146 #define IP_MAXFRAGPACKETS (imin(IP_MAXFRAGS, V_ipq_hashsize * 50))
147
148 static int maxfrags;
149 static u_int __exclusive_cache_line nfrags;
150 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfrags, CTLFLAG_RW,
151 &maxfrags, 0,
152 "Maximum number of IPv4 fragments allowed across all reassembly queues");
153 SYSCTL_UINT(_net_inet_ip, OID_AUTO, curfrags, CTLFLAG_RD,
154 &nfrags, 0,
155 "Current number of IPv4 fragments across all reassembly queues");
156
157 VNET_DEFINE_STATIC(uma_zone_t, ipq_zone);
158 #define V_ipq_zone VNET(ipq_zone)
159
160 SYSCTL_UINT(_net_inet_ip, OID_AUTO, reass_hashsize,
161 CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(ipq_hashsize), 0,
162 "Size of IP fragment reassembly hashtable");
163
164 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets,
165 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
166 NULL, 0, sysctl_maxfragpackets, "I",
167 "Maximum number of IPv4 fragment reassembly queue entries");
168 SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET,
169 &VNET_NAME(ipq_zone),
170 "Current number of IPv4 fragment reassembly queue entries");
171
172 VNET_DEFINE_STATIC(int, noreass);
173 #define V_noreass VNET(noreass)
174
175 VNET_DEFINE_STATIC(int, maxfragsperpacket);
176 #define V_maxfragsperpacket VNET(maxfragsperpacket)
177 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW,
178 &VNET_NAME(maxfragsperpacket), 0,
179 "Maximum number of IPv4 fragments allowed per packet");
180 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
181 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
182 sysctl_maxfragbucketsize, "I",
183 "Maximum number of IPv4 fragment reassembly queue entries per bucket");
184
185 VNET_DEFINE_STATIC(u_int, ipfragttl) = 30;
186 #define V_ipfragttl VNET(ipfragttl)
187 SYSCTL_PROC(_net_inet_ip, OID_AUTO, fragttl, CTLTYPE_INT | CTLFLAG_RW |
188 CTLFLAG_MPSAFE | CTLFLAG_VNET, NULL, 0, sysctl_fragttl, "IU",
189 "IP fragment life time on reassembly queue (seconds)");
190
191 /*
192 * Take incoming datagram fragment and try to reassemble it into
193 * whole datagram. If the argument is the first fragment or one
194 * in between the function will return NULL and store the mbuf
195 * in the fragment chain. If the argument is the last fragment
196 * the packet will be reassembled and the pointer to the new
197 * mbuf returned for further processing. Only m_tags attached
198 * to the first packet/fragment are preserved.
199 * The IP header is *NOT* adjusted out of iplen.
200 */
201 #define M_IP_FRAG M_PROTO9
202 struct mbuf *
ip_reass(struct mbuf * m)203 ip_reass(struct mbuf *m)
204 {
205 struct ip *ip;
206 struct mbuf *p, *q, *nq, *t;
207 struct ipq *fp;
208 struct ifnet *srcifp;
209 struct ipqhead *head;
210 int i, hlen, next, tmpmax;
211 u_int8_t ecn, ecn0;
212 uint32_t hash, hashkey[3];
213 #ifdef RSS
214 uint32_t rss_hash, rss_type;
215 #endif
216
217 /*
218 * If no reassembling or maxfragsperpacket are 0,
219 * never accept fragments.
220 * Also, drop packet if it would exceed the maximum
221 * number of fragments.
222 */
223 tmpmax = maxfrags;
224 if (V_noreass == 1 || V_maxfragsperpacket == 0 ||
225 (tmpmax >= 0 && atomic_load_int(&nfrags) >= (u_int)tmpmax)) {
226 IPSTAT_INC(ips_fragments);
227 IPSTAT_INC(ips_fragdropped);
228 m_freem(m);
229 return (NULL);
230 }
231
232 ip = mtod(m, struct ip *);
233 hlen = ip->ip_hl << 2;
234
235 /*
236 * Adjust ip_len to not reflect header,
237 * convert offset of this to bytes.
238 */
239 ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
240 /*
241 * Make sure that fragments have a data length
242 * that's a non-zero multiple of 8 bytes, unless
243 * this is the last fragment.
244 */
245 if (ip->ip_len == htons(0) ||
246 ((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) {
247 IPSTAT_INC(ips_toosmall); /* XXX */
248 IPSTAT_INC(ips_fragdropped);
249 m_freem(m);
250 return (NULL);
251 }
252 if (ip->ip_off & htons(IP_MF))
253 m->m_flags |= M_IP_FRAG;
254 else
255 m->m_flags &= ~M_IP_FRAG;
256 ip->ip_off = htons(ntohs(ip->ip_off) << 3);
257
258 /*
259 * Make sure the fragment lies within a packet of valid size.
260 */
261 if (ntohs(ip->ip_len) + ntohs(ip->ip_off) > IP_MAXPACKET) {
262 IPSTAT_INC(ips_toolong);
263 IPSTAT_INC(ips_fragdropped);
264 m_freem(m);
265 return (NULL);
266 }
267
268 /*
269 * Store receive network interface pointer for later.
270 */
271 srcifp = m->m_pkthdr.rcvif;
272
273 /*
274 * Attempt reassembly; if it succeeds, proceed.
275 * ip_reass() will return a different mbuf.
276 */
277 IPSTAT_INC(ips_fragments);
278 m->m_pkthdr.PH_loc.ptr = ip;
279
280 /*
281 * Presence of header sizes in mbufs
282 * would confuse code below.
283 */
284 m->m_data += hlen;
285 m->m_len -= hlen;
286
287 hashkey[0] = ip->ip_src.s_addr;
288 hashkey[1] = ip->ip_dst.s_addr;
289 hashkey[2] = (uint32_t)ip->ip_p << 16;
290 hashkey[2] += ip->ip_id;
291 hash = jenkins_hash32(hashkey, nitems(hashkey), V_ipq_hashseed);
292 hash &= IPREASS_HMASK;
293 head = &V_ipq[hash].head;
294 IPQ_LOCK(hash);
295
296 /*
297 * Look for queue of fragments
298 * of this datagram.
299 */
300 TAILQ_FOREACH(fp, head, ipq_list)
301 if (ip->ip_id == fp->ipq_id &&
302 ip->ip_src.s_addr == fp->ipq_src.s_addr &&
303 ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
304 #ifdef MAC
305 mac_ipq_match(m, fp) &&
306 #endif
307 ip->ip_p == fp->ipq_p)
308 break;
309 /*
310 * If first fragment to arrive, create a reassembly queue.
311 */
312 if (fp == NULL) {
313 if (V_ipq[hash].count < V_ipreass_maxbucketsize)
314 fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
315 if (fp == NULL)
316 fp = ipq_reuse(hash);
317 if (fp == NULL)
318 goto dropfrag;
319 #ifdef MAC
320 if (mac_ipq_init(fp, M_NOWAIT) != 0) {
321 uma_zfree(V_ipq_zone, fp);
322 fp = NULL;
323 goto dropfrag;
324 }
325 mac_ipq_create(m, fp);
326 #endif
327 TAILQ_INSERT_HEAD(head, fp, ipq_list);
328 V_ipq[hash].count++;
329 fp->ipq_nfrags = 1;
330 atomic_add_int(&nfrags, 1);
331 fp->ipq_expire = time_uptime + V_ipfragttl;
332 fp->ipq_p = ip->ip_p;
333 fp->ipq_id = ip->ip_id;
334 fp->ipq_src = ip->ip_src;
335 fp->ipq_dst = ip->ip_dst;
336 fp->ipq_frags = m;
337 if (m->m_flags & M_IP_FRAG)
338 fp->ipq_maxoff = -1;
339 else
340 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
341 m->m_nextpkt = NULL;
342 if (fp == TAILQ_LAST(head, ipqhead))
343 callout_reset_sbt(&V_ipq[hash].timer,
344 SBT_1S * V_ipfragttl, SBT_1S, ipreass_callout,
345 &V_ipq[hash], 0);
346 else
347 MPASS(callout_active(&V_ipq[hash].timer));
348 goto done;
349 } else {
350 /*
351 * If we already saw the last fragment, make sure
352 * this fragment's offset looks sane. Otherwise, if
353 * this is the last fragment, record its endpoint.
354 */
355 if (fp->ipq_maxoff > 0) {
356 i = ntohs(ip->ip_off) + ntohs(ip->ip_len);
357 if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) ||
358 ((m->m_flags & M_IP_FRAG) == 0 &&
359 i != fp->ipq_maxoff)) {
360 fp = NULL;
361 goto dropfrag;
362 }
363 } else if ((m->m_flags & M_IP_FRAG) == 0)
364 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
365 fp->ipq_nfrags++;
366 atomic_add_int(&nfrags, 1);
367 #ifdef MAC
368 mac_ipq_update(m, fp);
369 #endif
370 }
371
372 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr))
373
374 /*
375 * Handle ECN by comparing this segment with the first one;
376 * if CE is set, do not lose CE.
377 * drop if CE and not-ECT are mixed for the same packet.
378 */
379 ecn = ip->ip_tos & IPTOS_ECN_MASK;
380 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
381 if (ecn == IPTOS_ECN_CE) {
382 if (ecn0 == IPTOS_ECN_NOTECT)
383 goto dropfrag;
384 if (ecn0 != IPTOS_ECN_CE)
385 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
386 }
387 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
388 goto dropfrag;
389
390 /*
391 * Find a segment which begins after this one does.
392 */
393 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
394 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
395 break;
396
397 /*
398 * If there is a preceding segment, it may provide some of
399 * our data already. If so, drop the data from the incoming
400 * segment. If it provides all of our data, drop us, otherwise
401 * stick new segment in the proper place.
402 *
403 * If some of the data is dropped from the preceding
404 * segment, then it's checksum is invalidated.
405 */
406 if (p) {
407 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
408 ntohs(ip->ip_off);
409 if (i > 0) {
410 if (i >= ntohs(ip->ip_len))
411 goto dropfrag;
412 m_adj(m, i);
413 m->m_pkthdr.csum_flags = 0;
414 ip->ip_off = htons(ntohs(ip->ip_off) + i);
415 ip->ip_len = htons(ntohs(ip->ip_len) - i);
416 }
417 m->m_nextpkt = p->m_nextpkt;
418 p->m_nextpkt = m;
419 } else {
420 m->m_nextpkt = fp->ipq_frags;
421 fp->ipq_frags = m;
422 }
423
424 /*
425 * While we overlap succeeding segments trim them or,
426 * if they are completely covered, dequeue them.
427 */
428 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
429 ntohs(GETIP(q)->ip_off); q = nq) {
430 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
431 ntohs(GETIP(q)->ip_off);
432 if (i < ntohs(GETIP(q)->ip_len)) {
433 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
434 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
435 m_adj(q, i);
436 q->m_pkthdr.csum_flags = 0;
437 break;
438 }
439 nq = q->m_nextpkt;
440 m->m_nextpkt = nq;
441 IPSTAT_INC(ips_fragdropped);
442 fp->ipq_nfrags--;
443 atomic_subtract_int(&nfrags, 1);
444 m_freem(q);
445 }
446
447 /*
448 * Check for complete reassembly and perform frag per packet
449 * limiting.
450 *
451 * Frag limiting is performed here so that the nth frag has
452 * a chance to complete the packet before we drop the packet.
453 * As a result, n+1 frags are actually allowed per packet, but
454 * only n will ever be stored. (n = maxfragsperpacket.)
455 *
456 */
457 next = 0;
458 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
459 if (ntohs(GETIP(q)->ip_off) != next) {
460 if (fp->ipq_nfrags > V_maxfragsperpacket)
461 ipq_drop(&V_ipq[hash], fp);
462 goto done;
463 }
464 next += ntohs(GETIP(q)->ip_len);
465 }
466 /* Make sure the last packet didn't have the IP_MF flag */
467 if (p->m_flags & M_IP_FRAG) {
468 if (fp->ipq_nfrags > V_maxfragsperpacket)
469 ipq_drop(&V_ipq[hash], fp);
470 goto done;
471 }
472
473 /*
474 * Reassembly is complete. Make sure the packet is a sane size.
475 */
476 q = fp->ipq_frags;
477 ip = GETIP(q);
478 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
479 IPSTAT_INC(ips_toolong);
480 ipq_drop(&V_ipq[hash], fp);
481 goto done;
482 }
483
484 /*
485 * Concatenate fragments.
486 */
487 m = q;
488 t = m->m_next;
489 m->m_next = NULL;
490 m_cat(m, t);
491 nq = q->m_nextpkt;
492 q->m_nextpkt = NULL;
493 for (q = nq; q != NULL; q = nq) {
494 nq = q->m_nextpkt;
495 q->m_nextpkt = NULL;
496 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
497 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
498 m_demote_pkthdr(q);
499 m_cat(m, q);
500 }
501 /*
502 * In order to do checksumming faster we do 'end-around carry' here
503 * (and not in for{} loop), though it implies we are not going to
504 * reassemble more than 64k fragments.
505 */
506 while (m->m_pkthdr.csum_data & 0xffff0000)
507 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
508 (m->m_pkthdr.csum_data >> 16);
509 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
510 #ifdef MAC
511 mac_ipq_reassemble(fp, m);
512 mac_ipq_destroy(fp);
513 #endif
514
515 /*
516 * Create header for new ip packet by modifying header of first
517 * packet; dequeue and discard fragment reassembly header.
518 * Make header visible.
519 */
520 ip->ip_len = htons((ip->ip_hl << 2) + next);
521 ip->ip_src = fp->ipq_src;
522 ip->ip_dst = fp->ipq_dst;
523 TAILQ_REMOVE(head, fp, ipq_list);
524 V_ipq[hash].count--;
525 uma_zfree(V_ipq_zone, fp);
526 m->m_len += (ip->ip_hl << 2);
527 m->m_data -= (ip->ip_hl << 2);
528 /* some debugging cruft by sklower, below, will go away soon */
529 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
530 m_fixhdr(m);
531 /* set valid receive interface pointer */
532 m->m_pkthdr.rcvif = srcifp;
533 }
534 IPSTAT_INC(ips_reassembled);
535 ipreass_reschedule(&V_ipq[hash]);
536 IPQ_UNLOCK(hash);
537
538 #ifdef RSS
539 /*
540 * Query the RSS layer for the flowid / flowtype for the
541 * mbuf payload.
542 *
543 * For now, just assume we have to calculate a new one.
544 * Later on we should check to see if the assigned flowid matches
545 * what RSS wants for the given IP protocol and if so, just keep it.
546 *
547 * We then queue into the relevant netisr so it can be dispatched
548 * to the correct CPU.
549 *
550 * Note - this may return 1, which means the flowid in the mbuf
551 * is correct for the configured RSS hash types and can be used.
552 */
553 if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) {
554 m->m_pkthdr.flowid = rss_hash;
555 M_HASHTYPE_SET(m, rss_type);
556 }
557
558 /*
559 * Queue/dispatch for reprocessing.
560 *
561 * Note: this is much slower than just handling the frame in the
562 * current receive context. It's likely worth investigating
563 * why this is.
564 */
565 netisr_dispatch(NETISR_IP_DIRECT, m);
566 return (NULL);
567 #endif
568
569 /* Handle in-line */
570 return (m);
571
572 dropfrag:
573 IPSTAT_INC(ips_fragdropped);
574 if (fp != NULL) {
575 fp->ipq_nfrags--;
576 atomic_subtract_int(&nfrags, 1);
577 }
578 m_freem(m);
579 done:
580 IPQ_UNLOCK(hash);
581 return (NULL);
582
583 #undef GETIP
584 }
585
586 /*
587 * Timer expired on a bucket.
588 * There should be at least one ipq to be timed out.
589 */
590 static void
ipreass_callout(void * arg)591 ipreass_callout(void *arg)
592 {
593 struct ipqbucket *bucket = arg;
594 struct ipq *fp;
595
596 IPQ_BUCKET_LOCK_ASSERT(bucket);
597 MPASS(atomic_load_int(&nfrags) > 0);
598
599 CURVNET_SET(bucket->vnet);
600 fp = TAILQ_LAST(&bucket->head, ipqhead);
601 KASSERT(fp != NULL && fp->ipq_expire <= time_uptime,
602 ("%s: stray callout on bucket %p, %ju < %ju", __func__, bucket,
603 fp ? (uintmax_t)fp->ipq_expire : 0, (uintmax_t)time_uptime));
604
605 while (fp != NULL && fp->ipq_expire <= time_uptime) {
606 ipq_timeout(bucket, fp);
607 fp = TAILQ_LAST(&bucket->head, ipqhead);
608 }
609 ipreass_reschedule(bucket);
610 CURVNET_RESTORE();
611 }
612
613 static void
ipreass_reschedule(struct ipqbucket * bucket)614 ipreass_reschedule(struct ipqbucket *bucket)
615 {
616 struct ipq *fp;
617
618 IPQ_BUCKET_LOCK_ASSERT(bucket);
619
620 if ((fp = TAILQ_LAST(&bucket->head, ipqhead)) != NULL) {
621 time_t t;
622
623 /* Protect against time_uptime tick. */
624 t = fp->ipq_expire - time_uptime;
625 t = (t > 0) ? t : 1;
626 callout_reset_sbt(&bucket->timer, SBT_1S * t, SBT_1S,
627 ipreass_callout, bucket, 0);
628 } else
629 callout_stop(&bucket->timer);
630 }
631
632 static void
ipreass_drain_vnet(void)633 ipreass_drain_vnet(void)
634 {
635 u_int dropped = 0;
636
637 for (int i = 0; i < V_ipq_hashsize; i++) {
638 bool resched;
639
640 IPQ_LOCK(i);
641 resched = !TAILQ_EMPTY(&V_ipq[i].head);
642 while(!TAILQ_EMPTY(&V_ipq[i].head)) {
643 struct ipq *fp = TAILQ_FIRST(&V_ipq[i].head);
644
645 dropped += fp->ipq_nfrags;
646 ipq_free(&V_ipq[i], fp);
647 }
648 if (resched)
649 ipreass_reschedule(&V_ipq[i]);
650 KASSERT(V_ipq[i].count == 0,
651 ("%s: V_ipq[%d] count %d (V_ipq=%p)", __func__, i,
652 V_ipq[i].count, V_ipq));
653 IPQ_UNLOCK(i);
654 }
655 IPSTAT_ADD(ips_fragdropped, dropped);
656 }
657
658 /*
659 * Drain off all datagram fragments.
660 */
661 static void
ipreass_drain(void)662 ipreass_drain(void)
663 {
664 VNET_ITERATOR_DECL(vnet_iter);
665
666 VNET_LIST_RLOCK();
667 VNET_FOREACH(vnet_iter) {
668 CURVNET_SET(vnet_iter);
669 ipreass_drain_vnet();
670 CURVNET_RESTORE();
671 }
672 VNET_LIST_RUNLOCK();
673 }
674
675
676 /*
677 * Initialize IP reassembly structures.
678 */
679 MALLOC_DEFINE(M_IPREASS_HASH, "IP reass", "IP packet reassembly hash headers");
680 void
ipreass_vnet_init(void)681 ipreass_vnet_init(void)
682 {
683 int max;
684
685 V_ipq_hashsize = IPREASS_NHASH;
686 TUNABLE_INT_FETCH("net.inet.ip.reass_hashsize", &V_ipq_hashsize);
687 V_ipq = malloc(sizeof(struct ipqbucket) * V_ipq_hashsize,
688 M_IPREASS_HASH, M_WAITOK);
689
690 for (int i = 0; i < V_ipq_hashsize; i++) {
691 TAILQ_INIT(&V_ipq[i].head);
692 mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
693 MTX_DEF | MTX_DUPOK | MTX_NEW);
694 callout_init_mtx(&V_ipq[i].timer, &V_ipq[i].lock, 0);
695 V_ipq[i].count = 0;
696 #ifdef VIMAGE
697 V_ipq[i].vnet = curvnet;
698 #endif
699 }
700 V_ipq_hashseed = arc4random();
701 V_maxfragsperpacket = 16;
702 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
703 NULL, UMA_ALIGN_PTR, 0);
704 max = IP_MAXFRAGPACKETS;
705 max = uma_zone_set_max(V_ipq_zone, max);
706 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
707 }
708
709 void
ipreass_init(void)710 ipreass_init(void)
711 {
712
713 maxfrags = IP_MAXFRAGS;
714 EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change,
715 NULL, EVENTHANDLER_PRI_ANY);
716 EVENTHANDLER_REGISTER(vm_lowmem, ipreass_drain, NULL,
717 LOWMEM_PRI_DEFAULT);
718 EVENTHANDLER_REGISTER(mbuf_lowmem, ipreass_drain, NULL,
719 LOWMEM_PRI_DEFAULT);
720 }
721
722 /*
723 * Drain off all datagram fragments belonging to
724 * the given network interface.
725 */
726 static void
ipreass_cleanup(void * arg __unused,struct ifnet * ifp)727 ipreass_cleanup(void *arg __unused, struct ifnet *ifp)
728 {
729 struct ipq *fp, *temp;
730 struct mbuf *m;
731 int i;
732
733 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
734
735 CURVNET_SET_QUIET(ifp->if_vnet);
736
737 /*
738 * Skip processing if IPv4 reassembly is not initialised or
739 * torn down by ipreass_destroy().
740 */
741 if (V_ipq_zone == NULL) {
742 CURVNET_RESTORE();
743 return;
744 }
745
746 for (i = 0; i < V_ipq_hashsize; i++) {
747 IPQ_LOCK(i);
748 /* Scan fragment list. */
749 TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, temp) {
750 for (m = fp->ipq_frags; m != NULL; m = m->m_nextpkt) {
751 /* clear no longer valid rcvif pointer */
752 if (m->m_pkthdr.rcvif == ifp)
753 m->m_pkthdr.rcvif = NULL;
754 }
755 }
756 IPQ_UNLOCK(i);
757 }
758 CURVNET_RESTORE();
759 }
760 EVENTHANDLER_DEFINE(ifnet_departure_event, ipreass_cleanup, NULL, 0);
761
762 #ifdef VIMAGE
763 /*
764 * Destroy IP reassembly structures.
765 */
766 void
ipreass_destroy(void)767 ipreass_destroy(void)
768 {
769
770 ipreass_drain_vnet();
771 uma_zdestroy(V_ipq_zone);
772 V_ipq_zone = NULL;
773 for (int i = 0; i < V_ipq_hashsize; i++)
774 mtx_destroy(&V_ipq[i].lock);
775 free(V_ipq, M_IPREASS_HASH);
776 }
777 #endif
778
779 /*
780 * After maxnipq has been updated, propagate the change to UMA. The UMA zone
781 * max has slightly different semantics than the sysctl, for historical
782 * reasons.
783 */
784 static void
ipreass_drain_tomax(void)785 ipreass_drain_tomax(void)
786 {
787 struct ipq *fp;
788 int target;
789
790 /*
791 * Make sure each bucket is under the new limit. If
792 * necessary, drop enough of the oldest elements from
793 * each bucket to get under the new limit.
794 */
795 for (int i = 0; i < V_ipq_hashsize; i++) {
796 IPQ_LOCK(i);
797 while (V_ipq[i].count > V_ipreass_maxbucketsize &&
798 (fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL)
799 ipq_timeout(&V_ipq[i], fp);
800 ipreass_reschedule(&V_ipq[i]);
801 IPQ_UNLOCK(i);
802 }
803
804 /*
805 * If we are over the maximum number of fragments,
806 * drain off enough to get down to the new limit,
807 * stripping off last elements on queues. Every
808 * run we strip the oldest element from each bucket.
809 */
810 target = uma_zone_get_max(V_ipq_zone);
811 while (uma_zone_get_cur(V_ipq_zone) > target) {
812 for (int i = 0; i < V_ipq_hashsize; i++) {
813 IPQ_LOCK(i);
814 fp = TAILQ_LAST(&V_ipq[i].head, ipqhead);
815 if (fp != NULL) {
816 ipq_timeout(&V_ipq[i], fp);
817 ipreass_reschedule(&V_ipq[i]);
818 }
819 IPQ_UNLOCK(i);
820 }
821 }
822 }
823
824 static void
ipreass_zone_change(void * tag)825 ipreass_zone_change(void *tag)
826 {
827 VNET_ITERATOR_DECL(vnet_iter);
828 int max;
829
830 maxfrags = IP_MAXFRAGS;
831 max = IP_MAXFRAGPACKETS;
832 VNET_LIST_RLOCK_NOSLEEP();
833 VNET_FOREACH(vnet_iter) {
834 CURVNET_SET(vnet_iter);
835 max = uma_zone_set_max(V_ipq_zone, max);
836 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
837 ipreass_drain_tomax();
838 CURVNET_RESTORE();
839 }
840 VNET_LIST_RUNLOCK_NOSLEEP();
841 }
842
843 /*
844 * Change the limit on the UMA zone, or disable the fragment allocation
845 * at all. Since 0 and -1 is a special values here, we need our own handler,
846 * instead of sysctl_handle_uma_zone_max().
847 */
848 static int
sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)849 sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)
850 {
851 int error, max;
852
853 if (V_noreass == 0) {
854 max = uma_zone_get_max(V_ipq_zone);
855 if (max == 0)
856 max = -1;
857 } else
858 max = 0;
859 error = sysctl_handle_int(oidp, &max, 0, req);
860 if (error || !req->newptr)
861 return (error);
862 if (max > 0) {
863 /*
864 * XXXRW: Might be a good idea to sanity check the argument
865 * and place an extreme upper bound.
866 */
867 max = uma_zone_set_max(V_ipq_zone, max);
868 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
869 ipreass_drain_tomax();
870 V_noreass = 0;
871 } else if (max == 0) {
872 V_noreass = 1;
873 ipreass_drain();
874 } else if (max == -1) {
875 V_noreass = 0;
876 uma_zone_set_max(V_ipq_zone, 0);
877 V_ipreass_maxbucketsize = INT_MAX;
878 } else
879 return (EINVAL);
880 return (0);
881 }
882
883 /*
884 * Seek for old fragment queue header that can be reused. Try to
885 * reuse a header from currently locked hash bucket.
886 */
887 static struct ipq *
ipq_reuse(int start)888 ipq_reuse(int start)
889 {
890 struct ipq *fp;
891 int bucket, i;
892
893 IPQ_LOCK_ASSERT(start);
894
895 for (i = 0; i < V_ipq_hashsize; i++) {
896 bucket = (start + i) % V_ipq_hashsize;
897 if (bucket != start && IPQ_TRYLOCK(bucket) == 0)
898 continue;
899 fp = TAILQ_LAST(&V_ipq[bucket].head, ipqhead);
900 if (fp) {
901 struct mbuf *m;
902
903 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
904 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
905 while (fp->ipq_frags) {
906 m = fp->ipq_frags;
907 fp->ipq_frags = m->m_nextpkt;
908 m_freem(m);
909 }
910 TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list);
911 V_ipq[bucket].count--;
912 ipreass_reschedule(&V_ipq[bucket]);
913 if (bucket != start)
914 IPQ_UNLOCK(bucket);
915 break;
916 }
917 if (bucket != start)
918 IPQ_UNLOCK(bucket);
919 }
920 IPQ_LOCK_ASSERT(start);
921 return (fp);
922 }
923
924 /*
925 * Free a fragment reassembly header and all associated datagrams.
926 */
927 static void
ipq_free(struct ipqbucket * bucket,struct ipq * fp)928 ipq_free(struct ipqbucket *bucket, struct ipq *fp)
929 {
930 struct mbuf *q;
931
932 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
933 while (fp->ipq_frags) {
934 q = fp->ipq_frags;
935 fp->ipq_frags = q->m_nextpkt;
936 m_freem(q);
937 }
938 TAILQ_REMOVE(&bucket->head, fp, ipq_list);
939 bucket->count--;
940 uma_zfree(V_ipq_zone, fp);
941 }
942
943 /*
944 * Get or set the maximum number of reassembly queues per bucket.
945 */
946 static int
sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)947 sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)
948 {
949 int error, max;
950
951 max = V_ipreass_maxbucketsize;
952 error = sysctl_handle_int(oidp, &max, 0, req);
953 if (error || !req->newptr)
954 return (error);
955 if (max <= 0)
956 return (EINVAL);
957 V_ipreass_maxbucketsize = max;
958 ipreass_drain_tomax();
959 return (0);
960 }
961
962 /*
963 * Get or set the IP fragment time to live.
964 */
965 static int
sysctl_fragttl(SYSCTL_HANDLER_ARGS)966 sysctl_fragttl(SYSCTL_HANDLER_ARGS)
967 {
968 u_int ttl;
969 int error;
970
971 ttl = V_ipfragttl;
972 error = sysctl_handle_int(oidp, &ttl, 0, req);
973 if (error || !req->newptr)
974 return (error);
975
976 if (ttl < 1 || ttl > MAXTTL)
977 return (EINVAL);
978
979 atomic_store_int(&V_ipfragttl, ttl);
980 return (0);
981 }
982